US6642817B2 - Dielectric filter, dielectric duplexer, and communication device - Google Patents

Dielectric filter, dielectric duplexer, and communication device Download PDF

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Publication number
US6642817B2
US6642817B2 US10/076,724 US7672402A US6642817B2 US 6642817 B2 US6642817 B2 US 6642817B2 US 7672402 A US7672402 A US 7672402A US 6642817 B2 US6642817 B2 US 6642817B2
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conductor
dielectric
electrodes
conductor holes
holes
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US20020109567A1 (en
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Katsuhito Kuroda
Hirofumi Miyamoto
Jinsei Ishihara
Hideyuki Kato
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/205—Comb or interdigital filters; Cascaded coaxial cavities
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/205—Comb or interdigital filters; Cascaded coaxial cavities
    • H01P1/2056—Comb filters or interdigital filters with metallised resonator holes in a dielectric block
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/213—Frequency-selective devices, e.g. filters combining or separating two or more different frequencies
    • H01P1/2136—Frequency-selective devices, e.g. filters combining or separating two or more different frequencies using comb or interdigital filters; using cascaded coaxial cavities

Definitions

  • the present invention relates to a dielectric filter and a dielectric duplexer which comprise a dielectric block having holes with conductors formed on the surfaces of the holes (hereinafter referred to as inner-conductor holes) and an outer conductor on the outer surface of the dielectric block, and to a communication device using the dielectric filter and the dielectric duplexer.
  • a known dielectric filter having a substantially rectangular parallelepiped dielectric block will now be described with reference to FIGS. 7A and 7B.
  • FIG. 7A is a perspective view of the dielectric filter
  • FIG. 7B is a leftside elevational view of the same.
  • the dielectric filter includes a dielectric block 1 , inner-conductor holes 2 a , 2 b , 2 c , and 2 d , inner conductors 3 a , 3 b , 3 c , and 3 d , an outer conductor 4 , input and output (I/O) electrodes 5 a and 5 b , and dielectric resonators 6 a , 6 b , 6 c , and 6 d.
  • I/O input and output
  • the inner-conductor holes 2 a to 2 d which have the inner conductors 3 a to 3 c on the surfaces thereof, form resonators.
  • the outer conductor 4 forms a ground electrode. In this manner, the inner-conductor holes 2 a to 2 d and the outer conductor 4 form the dielectric resonators 6 a to 6 d .
  • the I/O electrode 5 a is formed separate from the outer conductor 4 and is coupled with the dielectric resonator 6 a (hereinafter referred to as the resonator), and the I/O electrode 5 b is formed separate from the outer conductor 4 and is coupled with the resonator 6 d , whereby the dielectric filter is formed.
  • bandpass filters must obtain a predetermined attenuation far outside the pass band.
  • an attenuation pole is provided in the attenuation region of the bandpass filters.
  • the I/O electrode 5 a is coupled with the resonator 6 a and the I/O electrode 5 b is coupled with the resonator 6 d . Since the amount of coupling between the resonator 6 a and the resonator 6 b , and between the resonator 6 c and the resonator 6 d is small, the resonators are not sufficiently capacitively coupled. Therefore, an effective attenuation pole is not obtained. To obtain a sufficient amount of coupling, a capacitor must be provided between the resonator 6 a and the resonator 6 b , and between the resonator 6 c and the resonator 6 d . Accordingly, the manufacturing costs increase due to the increase in the number of parts, and the reliability deteriorates because of the increase in the number of connections.
  • the dielectric filter comprises a dielectric block having a plurality of dielectric resonators.
  • the dielectric block has I/O electrodes on the outer surface thereof, which are coupled with the plurality of dielectric resonators. According to this configuration, since the amount of coupling between the plurality of resonators and between the plurality of resonators and the I/O electrodes becomes large, the attenuation region is provided with a pole, making the attenuation curve steeper by forming an attenuation pole near the pass band. Thus, a bandpass filter capable of sufficiently attenuating unwanted signals is provided.
  • the size of the I/O electrodes may vary according to manufacturing tolerances. In such a case, the amount of coupling between the second resonator and the I/O electrode varies, rendering the attenuation characteristics unstable.
  • the width of the I/O electrodes (the dimension of the I/O electrodes parallel to the axes of the inner-conductor holes) is large, the Qo factor of the resonators deteriorates, and the insertion loss increases. Further, since the width of the I/O electrodes is fixed, a dielectric filter formed in a certain shape exhibits only one kind of attenuation characteristic. In other words, the dielectric filter is not capable of exhibiting a plurality of attenuation characteristics for achieving desired characteristics.
  • the present invention provides a dielectric filter and a dielectric duplexer, which exhibit suitable attenuation characteristics and which readily obtain desired characteristics, and provides a communication device using the dielectric filter and the dielectric duplexer.
  • a dielectric filter comprising a substantially rectangular parallelepiped dielectric block, a plurality of inner-conductor holes extending from a first main surface to an opposing second main surface of the dielectric block, an inner conductor provided on the surface of each of the inner-conductor holes, an outer conductor formed on outer surfaces of the dielectric block, and I/O electrodes extending from side-surfaces to an undersurface of the dielectric block.
  • the side-surfaces are orthogonal to the direction in which the inner-conductor holes are arrayed in the dielectric block, and the undersurface is a mounting surface for facing a mounting board.
  • the I/O electrodes are separated from the outer conductor.
  • At least one of the I/O electrodes extends across portions of the undersurface of the dielectric block adjacent to at least two of the inner-conductor holes when viewed from the undersurface.
  • the dielectric filter obtained according to this configuration exhibits stable and suitable attenuation characteristics.
  • the width of the one of the I/O electrodes is different between a first region corresponding to the first inner-conductor hole and a second region corresponding to the second inner-conductor hole when viewed from the undersurface. According to this configuration, a dielectric filter is obtained, which readily obtains desired attenuation characteristics.
  • the width at the first region may be larger than the width at the second region. According to this configuration, a dielectric filter is obtained, which readily obtains desired attenuation characteristics.
  • the width at the first region may be smaller than the width at the second region. According to this configuration as well, a dielectric filter is obtained, which readily obtains desired attenuation characteristics.
  • a dielectric duplexer comprising the dielectric filter. According to this configuration, the dielectric duplexer exhibits desired characteristics, and stable and suitable attenuation characteristics are achieved.
  • a communication device comprising the dielectric filter. According to this configuration, the communication device exhibits suitable communication characteristics.
  • FIG. 1A is a perspective view of a dielectric filter according to a first embodiment
  • FIG. 1B is an elevational view of the dielectric filter according to the first embodiment
  • FIG. 2A is an equivalent circuit diagram of the dielectric filter according to the first embodiment
  • FIG. 2B is an equivalent circuit diagram of the dielectric filter according to the first embodiment
  • FIG. 3A is a perspective view of a dielectric filter according to a second embodiment
  • FIG. 3B is an elevational view of the dielectric filter according to the second embodiment
  • FIG. 4A is a perspective view of another dielectric filter according to the second embodiment
  • FIG. 4B is an elevational view of the other dielectric filter according to the second embodiment.
  • FIG. 5A is a perspective view of a dielectric duplexer according to a third embodiment
  • FIG. 5B is an elevational view of the dielectric duplexer according to the third embodiment.
  • FIG. 6 is a block diagram of a communication device according to a fourth embodiment.
  • FIG. 7A is a perspective view of a known dielectric filter.
  • FIG. 7B is an elevational view of the known dielectric filter.
  • FIGS. 1A and 1B and FIGS. 2A and 2B a dielectric filter according to a first embodiment will now be described.
  • FIG. 1A is a perspective view of the dielectric filter
  • FIG. 1B is an elevational view of the same.
  • the dielectric filter includes a dielectric block 1 , inner-conductor holes 2 a , 2 b and 2 c , inner conductors 3 a , 3 b and 3 c , an outer conductor 4 , input and output (I/O) electrodes 5 a and 5 b , and dielectric resonators (hereinafter referred to as resonators) 6 a , 6 b and 6 c.
  • resonators dielectric resonators
  • the inner-conductor holes 2 a to 2 c which have the inner conductors 3 a to 3 c formed on the surfaces thereof, form resonators.
  • the outer conductor 4 is formed as a ground electrode.
  • the inner-conductor holes 2 a to 2 c and the outer electrode 4 constitute the resonators 6 a to 6 c .
  • the I/O electrode 5 a extends from one side-surface to the undersurface of the dielectric block 1 and is separated from the outer conductor 4 .
  • the side-surfaces are orthogonal to the direction in which the inner-conductor holes are arrayed, and the undersurface is the surface shown in FIG.
  • the I/O electrode 5 b extends from the other side-surface to the undersurface of the dielectric block 1 and is separated from the outer conductor 4 .
  • the I/O electrode 5 a on the undersurface extends to a point a that is beyond a point b corresponding to the side of the inner-conductor hole 2 b near the inner-conductor hole 2 c.
  • the resonators 6 a to 6 c are aligned so that the resonator 6 b is positioned to the left of the resonator 6 a , and the resonator 6 c is positioned to the left of the resonator 6 b when viewed from the undersurface.
  • the I/O electrode 5 a is coupled with the inner-conductor holes 2 a and 2 b . It also means that the I/O electrode 5 a is coupled with the resonators 6 a and 6 b.
  • FIG. 2A shows an equivalent circuit diagram of the dielectric filter shown in FIGS. 1A and 1B.
  • FIG. 2B shows an equivalent circuit diagram obtained by converting the equivalent circuit shown in FIG. 2 A.
  • reference numerals 5 a and 5 b denote the I/O electrodes of the dielectric filter
  • reference numerals 6 a , 6 b and 6 c denote the resonators.
  • reference numerals Ca, Cb, Cc, Cx, and C 1 denote capacitances
  • reference numerals L 1 and L 2 denote inductances.
  • the capacitance Ca connects the I/O electrode 5 a with the resonator 6 a
  • the capacitance Cb connects the I/O electrode 5 a with the resonator 6 b
  • the capacitance Cx connects the resonator 6 a and the resonator 6 b
  • the capacitance Cc connects the I/O electrode 5 b with the resonator 6 c.
  • the circuit shown in FIG. 2A is a closed, D-shaped circuit comprising the three capacitances Ca, Cb and Cx, the circuit may be considered equivalent to a Y-shaped circuit as shown in FIG. 2B.
  • a series resonance is generated by the resonator 6 a and the inductor L 1 , whereby an attenuation pole is formed at a high frequency of the pass band.
  • the capacitance Cb Since the I/O electrode 5 a extends beyond the position corresponding to one side of the resonator 6 b , that is, the end near the resonator 6 c , the capacitance Cb becomes stable even when dimensional variations occur. Therefore, an attenuation pole is formed stably. Since the capacitance Cb is provided without enlarging the width of the I/O electrode 5 a , deterioration of the Qo factor and insertion loss is reduced.
  • the dielectric filter exhibits stable and suitable attenuation characteristics.
  • FIGS. 3A and 3B and FIGS. 4A and 4B a dielectric filter according to a second embodiment will now be described with reference to FIGS. 3A and 3B and FIGS. 4A and 4B.
  • FIG. 3A is a perspective view of a dielectric filter, while FIG. 3B is an elevational view of the same.
  • FIG. 4A is a perspective view of another dielectric filter, while FIG. 4B is an elevational view of the same.
  • the dielectric filter includes a dielectric block 1 , inner-conductor holes 2 a , 2 b and 2 c , inner conductors 3 a , 3 b and 3 c , an outer conductor 4 , I/O electrodes 5 a and 5 b , and dielectric resonators (hereinafter referred to as resonators) 6 a , 6 b and 6 c.
  • resonators dielectric resonators
  • the dielectric filter shown in FIGS. 3A and 3B is formed in the same manner as in the first embodiment, except that the shape of the I/O electrode 5 a is modified.
  • the side-surfaces of the dielectric block 1 are orthogonal to the direction in which the inner-conductor holes 2 a to 2 c are arrayed.
  • a point a corresponds to a position beyond a side of the inner-conductor hole 2 b , that is, the side near the inner-conductor hole 2 c .
  • a point b corresponds to a side of the inner-conductor hole 2 b , that is, the side near the inner-conductor hole 2 c .
  • the I/O electrode 5 a extends from one side-surface near the inner-conductor hole 2 a to the point a.
  • the width of the I/O electrode 5 a which is parallel to the axial direction of the inner-conductor holes, is smaller at the region where it is coupled with the resonator 6 b than at the region where it is coupled with the resonator 6 a.
  • a dielectric filter shown in FIG. 4A is formed in the same manner as in the first embodiment, except that the shape of the I/O electrode 5 a is modified. That is to say, the width of the I/O electrode 5 a at a region where it is coupled with the resonator 6 b is larger than at the region where it is coupled with the resonator 6 a.
  • the position of an attenuation pole may be changed by changing the coupling capacitance between the resonator 6 b and the I/O electrode 5 a . Subsequently, the dielectric filter readily and stably exhibits the desired characteristics.
  • the width of the I/O electrode 5 a at the region where the resonator 6 b is connected is narrow, the following effects may be obtained. That is to say, when the I/O electrode 5 a becomes long enough to cover the resonator 6 a and the resonator 6 b , the coupling capacitance obtained becomes much larger than desired.
  • the width of the I/O electrode 5 a at the region where the resonator 6 b is coupled narrow as shown in FIGS. 3A and 3B, the coupling capacitance can be reduced to a desired level.
  • the coupling capacitance can also be adjusted by making the I/O electrode 5 a shorter, the change resulting from this method becomes too large. In other words, it is very difficult to achieve fine adjustments simply by making the I/O electrode 5 a shorter. However, by adjusting the width of the I/O electrode 5 a at the region where it covers the inner-conductor holes as in this embodiment, it is easy to make fine adjustments and to reduce the coupling capacitance to a desired level.
  • each of the dielectric filters described in the first and the second embodiments has one of the openings of each of the inner-conductor holes 2 a to 2 c but no electrodes thereon. Thus, this surface functions as an open end of the dielectric filters.
  • other types of dielectric filter according to the present invention are possible.
  • one type of dielectric filter may comprise, on a surface having one of the openings of each inner-conductor hole, coupling electrodes for generating capacitance between the openings of neighboring inner-conductor holes.
  • Another type of dielectric filter may comprise an outer conductor formed on all surfaces of the dielectric block, and, near one of the surfaces which has one of the openings of each inner-conductor hole, each of the inner-conductor holes may have a region where no inner conductor is formed, these regions being provided near said openings of the inner-conductor holes. In this way, the regions of the inner-conductor holes where no conductor is formed function as open ends of the dielectric resonators.
  • the sectional shape of the inner-conductor holes is not limited to a circle, but may be an ellipse, a polygon and so forth.
  • a dielectric duplexer according to a third embodiment will now be described with reference to FIG. 5 A and FIG. 5 B.
  • FIG. 5A is a perspective view of the dielectric duplexer
  • FIG. 5B is an elevational view of the same.
  • the dielectric duplexer includes a dielectric block 1 , inner-conductor holes 2 a , 2 b , 2 c , 2 d , 2 e , and 2 f , inner conductors 3 a , 3 b , 3 c , 3 d , 3 e , and 3 f , an outer conductor 4 , I/O electrodes 5 a , 5 b and 5 c , and dielectric resonators (hereinafter referred to as resonators) 6 a , 6 b , 6 c , 6 d , 6 e , and 6 f.
  • resonators dielectric resonators
  • the inner-conductor holes 2 a to 2 f having the inner conductors 3 a to 3 f formed on the surfaces thereof, form resonator electrodes.
  • the outer conductor 4 forms a ground electrode.
  • the inner-conductor holes 2 a to 2 f and the outer electrode 4 constitute the dielectric resonators 6 a to 6 f .
  • the I/O electrode 5 a extends from one side-surface to the undersurface of the dielectric block 1 and is separated from the outer conductor 4 .
  • the side-surfaces are orthogonal to the direction in which the inner-conductor holes are arrayed, and the undersurface faces a mounting substrate (not shown) when the duplexer is mounted.
  • the I/O electrode 5 b extends from the other side-surface to the undersurface of the dielectric block 1 and is separated from the outer conductor 4 .
  • the I/O electrode 5 c is formed only on the undersurface, so as to couple with the resonators 6 c and 6 d.
  • the resonators 6 a to 6 f are arrayed so that the resonator 6 b is positioned to the left of the resonator 6 a , the resonator 6 c is positioned to the left of the resonator 6 b , the resonator 6 d is positioned to the left of the resonator 6 c , the resonator 6 e is positioned to the left of the resonator 6 d , and the resonator 6 f is positioned to the left of the resonator 6 e , when viewed from the undersurface as shown in FIGS. 5A and 5B. Further, as shown in FIG.
  • a point a corresponds to a side of the inner-conductor hole 2 b , that is, the side near the inner conductor 2 c
  • a point b corresponds to a side of the inner-conductor hole 2 e , that is, the side near the inner-conductor hole 2 d.
  • the I/O electrode 5 a on the undersurface extends from one side-surface to beyond the point a.
  • the width of the I/O electrode 5 a is smaller at the region where it is coupled with the resonator 6 b than at the region where it is coupled with the resonator 6 a .
  • the width is parallel to the axes of the inner-conductor holes.
  • the I/O electrode 5 b extends from the other side-surface to beyond the point b.
  • the width of the I/O electrode 5 b is smaller at the region where it is coupled with the resonator 6 e than at the region where it is coupled with the resonator 6 f .
  • the width is parallel to the axes of the inner-conductor holes.
  • the dielectric duplexer comprises a dielectric block which has a dielectric filter having the resonators 6 a and 6 b coupled with the I/O electrode 5 a , and the resonator 6 c coupled with the I/O electrode 5 c .
  • the dielectric filter also has another dielectric filter having the resonators 6 e and 6 f coupled with the I/O electrodes 5 b , and the resonator 6 d coupled with the I/O electrode 5 C.
  • the resulting dielectric duplexer exhibits desired characteristics, and suitable attenuation characteristics and stable communication characteristics are achieved.
  • the dielectric duplexer may have an open end at a surface having one of the openings of each of the inner-conductor holes, and coupling electrodes on that surface.
  • the duplexer may also be provided with an open end by providing a region where no inner conductor is formed on the surface of each of the inner-conductor holes.
  • sectional shape of the inner-conductor holes is not limited to a circle, but may be an ellipse, a polygon and so forth.
  • ANT denotes a transmission/reception antenna
  • DPX denotes a duplexer
  • BPFa and BPFb denote bandpass filters
  • AMPa and AMPb denote amplifier circuits
  • MIXa and MIXb denote mixers
  • OSC denotes an oscillator
  • SYN denotes a synthesizer
  • IF denotes an intermediate frequency signal.
  • the dielectric filters shown in FIGS. 1A and 1B, FIGS. 3A and 3B, and FIGS. 4A and 4B may be used.
  • the duplexer DPX shown in FIG. 6 the dielectric duplexer shown in FIGS. 5A and 5B may be used.
  • the communication device offers predetermined communication performance by comprising the dielectric filters and the dielectric duplexer having desired characteristics for achieving suitable and stable attenuation.

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  • Electromagnetism (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
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US10/076,724 2001-02-14 2002-02-13 Dielectric filter, dielectric duplexer, and communication device Expired - Lifetime US6642817B2 (en)

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JP2001036968A JP2002246805A (ja) 2001-02-14 2001-02-14 誘電体フィルタ、誘電体デュプレクサ、および通信装置
JP2001-036968 2001-02-14

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JP (1) JP2002246805A (ko)
KR (1) KR100401971B1 (ko)
CN (1) CN1212689C (ko)
FR (1) FR2820885B1 (ko)

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JP2002344204A (ja) * 2001-03-15 2002-11-29 Murata Mfg Co Ltd 誘電体フィルタ、誘電体デュプレクサおよび通信装置

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0495401A (ja) * 1990-08-10 1992-03-27 Murata Mfg Co Ltd 有極型誘電体フィルタ
JPH05145302A (ja) 1991-11-19 1993-06-11 Murata Mfg Co Ltd 誘電体共振器
US5949308A (en) * 1995-02-02 1999-09-07 Ngk Spark Plug Co., Ltd. Dielectric filter and method of regulating its frequency bandwidth via at least one insulation gap
EP0982792A2 (en) * 1998-08-25 2000-03-01 Murata Manufacturing Co., Ltd. Antenna duplexer and communication apparatus
US6052040A (en) * 1997-03-03 2000-04-18 Ngk Spark Plug Co., Ltd. Dielectric duplexer with different capacitive coupling between antenna pad and transmitting and receiving sections
US6069542A (en) * 1992-01-23 2000-05-30 Murata Manufacturing Co., Ltd. Dielectric filter having resonator electrodes, shield electrodes, and coupling electrodes disposed within a dielectric body
EP1030400A1 (en) * 1999-02-17 2000-08-23 Murata Manufacturing Co., Ltd. A dielectric filter, a dielectric duplexer, and a communication apparatus
US20020021189A1 (en) * 2000-08-10 2002-02-21 Murata Manufacturing Co., Ltd. Dielecric filter, dielectric duplexer, and commincation device using the same

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0495401A (ja) * 1990-08-10 1992-03-27 Murata Mfg Co Ltd 有極型誘電体フィルタ
JPH05145302A (ja) 1991-11-19 1993-06-11 Murata Mfg Co Ltd 誘電体共振器
US6069542A (en) * 1992-01-23 2000-05-30 Murata Manufacturing Co., Ltd. Dielectric filter having resonator electrodes, shield electrodes, and coupling electrodes disposed within a dielectric body
US5949308A (en) * 1995-02-02 1999-09-07 Ngk Spark Plug Co., Ltd. Dielectric filter and method of regulating its frequency bandwidth via at least one insulation gap
US6052040A (en) * 1997-03-03 2000-04-18 Ngk Spark Plug Co., Ltd. Dielectric duplexer with different capacitive coupling between antenna pad and transmitting and receiving sections
EP0982792A2 (en) * 1998-08-25 2000-03-01 Murata Manufacturing Co., Ltd. Antenna duplexer and communication apparatus
EP1030400A1 (en) * 1999-02-17 2000-08-23 Murata Manufacturing Co., Ltd. A dielectric filter, a dielectric duplexer, and a communication apparatus
US20020021189A1 (en) * 2000-08-10 2002-02-21 Murata Manufacturing Co., Ltd. Dielecric filter, dielectric duplexer, and commincation device using the same

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CN1371142A (zh) 2002-09-25
FR2820885B1 (fr) 2006-12-01
KR100401971B1 (ko) 2003-10-17
CN1212689C (zh) 2005-07-27
JP2002246805A (ja) 2002-08-30
KR20020067431A (ko) 2002-08-22
FR2820885A1 (fr) 2002-08-16
US20020109567A1 (en) 2002-08-15

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